Ideas to Make over Cobo Center

[Stosh]

It's not math. It's the requirements of the building codes.

So would it make any difference if there were not people allowed up there? There are people up there now when cars are parked up there, when a show lets out, fireworks, etc. Load requirements for parking garages elsewhere have dropped to 35-37 psf in some localities lately.

[ghettopalmetto]

So would it make any difference if there were not people allowed up there? There are people up there now when cars are parked up there, when a show lets out, fireworks, etc. Load requirements for parking garages elsewhere have dropped to 35-37 psf in some localities lately.

Yes, it changes quite a bit. Areas of assembly and pedestrian corridors must have a minimum live load capacity of 100 psf. This does not include the self-weight of the structure, rooftop HVAC equipment, or snow loads on a roof surface [[which, in Detroit, are at least 30 psf alone).

Please cite your source of information regarding the parking garages that have been designed to 35-37 psf. Michigan uses a statewide building code that does not allow localities to opt-out of particular provisions. The Michigan Building Code is essentially the same as the International Building Code [[2006 is the current version), with state-specific amendments. The International Building Code [[which incorporates ASCE 7 by reference) requires a minimum design live load of 50 psf for parking decks. I don't know any engineer willing to stake his career, or the public safety, on using a lower design value.

[Stosh]

Yes, it changes quite a bit. Areas of assembly and pedestrian corridors must have a minimum live load capacity of 100 psf. This does not include the self-weight of the structure, rooftop HVAC equipment, or snow loads on a roof surface [[which, in Detroit, are at least 30 psf alone).

Please cite your source of information regarding the parking garages that have been designed to 35-37 psf. Michigan uses a statewide building code that does not allow localities to opt-out of particular provisions. The Michigan Building Code is essentially the same as the International Building Code [[2006 is the current version), with state-specific amendments. The International Building Code [[which incorporates ASCE 7 by reference) requires a minimum design live load of 50 psf for parking decks. I don't know any engineer willing to stake his career, or the public safety, on using a lower design value.

Sorry. I was quoting speculation on a message board, here's a more realistic number. Still, 40 is a big reduction.
http://www.gostructural.com/magazine...oads-4221.html

Section 1607.9: Passenger Vehicle Parking Garage Live Loads
February 2006 » Columns » CODE SIMPLE

The International Code Council's 2003 International Building Code [[IBC) Table 1607.1, Item 16, sets forth a uniform live load of 40 pounds per square foot [[psf ) for passenger vehicle parking garages.
By S. K. Ghosh, Ph.D., Susan Dowty, S.E.
The International Code Council’s 2003 International Building Code [[IBC) Table 1607.1, Item 16, sets forth a uniform live load of 40 pounds per square foot [[psf ) for passenger vehicle parking garages, and "Footnote a" requires that garages restricted to vehicles accommodating not more than nine passengers be designed for a concentrated load of 3,000 pounds acting on an area of 4.5 inches by 4.5 inches. Both of these live loads were revised from those specified in the 2000 IBC, which were a live load of 50 psf and a concentrated load of 2,000 pounds acting on 20 square inches. The rationale for changing the live loads was based upon a publication which is available from the American Society of Civil Engineers [[ASCE), Design Live Loads for Parking Garages: A Report to the Structural Engineering Institute of the American Society of Civil Engineers by Y.K.Wen and G.L.Yeo.This study justified a reduction in the live load from 50 psf to 40 psf and an increase in the concentrated load due to very heavy passenger vehicles such as sport-utility vehicles. The 2003 IBC-prescribed loads are the same as those in ASCE 7-02 and —05, Minimum Design Loads for Buildings and Other Structures.

[ghettopalmetto]

I don't have IBC 2003 handy right now, but the way that article reads, it's not just a reduction to a uniform 40 psf live load from 50 psf. You also have to design for a 3000 lb concentrated load over a 4.5" x 4.5" area in addition to the uniform 40 psf surface live load.

Rather than design for the concentrated load in addition to the surface live load, the design engineer may be just as likely to use a uniform surface live load of 50 psf in his design.

[Stosh]

Also for information purposes, Minnesota's target center is beeing considered for a green roof as well. Quite informative.

http://www.ci.minneapolis.mn.us/coun...21-2-11-08.pdf